Preheat the oven to 350 degrees. Prepare a bread loaf pan (I swear by Pam with Flour!)
In a mixing bowl, melt the butter.
Add in the mashed bananas. (I just add the bananas to the bowl and mash them into the butter.)
Mix in the baking soda and salt.
Stir in the sugar, beaten egg, and vanilla extract.
Mix in the flour.
Fold in the blueberries - don't use the mixer, just mix by hand.
Pour the batter into the bread loaf pan. Bake for 50 minutes to 1 hour.
Remove from oven and cool completely. Remove the blueberry banana bread from the pan. Slice and serve.
To freeze: Let it cool, wrap up tight in plastic wrap, put into a freezer safe bag. Defrost when ready to serve!